The crossword solution for the term 'conjunction used in logic' is NOR, which is a three-letter word. NOR is a logical operator that is used to connect two statements or propositions in order to form a new statement. It is a type of conjunction that is used in logic and mathematics, and it is the opposite of the logical operator OR. When two statements are connected by NOR, the resulting statement is true only when both of the original statements are false.